We will continue work in the validation of one minute exercise testing at an antigravity power requirement of 1000 Kgm/min using a treadmill usually set at 53.6 m/min and a grade determined by formula 1000 equals Wgt (KG) times grade times walking speed. Faster speeds are used for lighter subjects so that grade does not exceed 30%. The standard measurement is oxygen uptake (VO2-1) measured in the last 15 seconds of the first minute timed from inspiration to inspiration with a minimum time of 12 seconds. A recently added measurement is cardiac output (CO-1) measured in separate runs at the same settings, using a rebreathing method designed by Dr. Leon Farhi at SUNY, Buffalo. Preliminary work has shown that reduced VO2-1 (less than 85% predicted) is usually associated with reduced CO-1 (less than 9.9 L/min) in subjects with coronary artery disease (CAD) but that reduced CO-1 may occur with normal VO2-1. We propose to investigate this further in a larger group of CAD subjects and see whether exercise programs can improve low VO2-1 and CO-1 values. These methods offer the possibility of detecting latent cardiac insufficiency in CAD subjects. BIBLIOGRAPHIC REFERENCES: "Response of Oxygen Uptake to Exercise in Coronary Artery Disease". J.H. Auchincloss, Robert Gilbert and Jane Bowman. CHEST. Vol. 65, p. 500-506, May, 1974.